NAPHN14 in Maine, Martin and a Few Inches of Sub-Slab Insulation

This is a guest blog post by Bronwyn Barry, a CPHD, Passive House California Board Member, and Co-President of the North American Passive House Network.

October 3, 2014

This past weekend saw a lively debate on Twitter between Martin Holladay, myself and a few other Tweeps over what amounts to a few inches of insulation. It followed a very successful North American Passive House Network 2014 (NAPHN14) Conference & Expo in Maine, where I had the pleasure of seeing Martin again along with a number of additional Twitter followers and friends.

Martin gave me a great compliment at NAPHN14 saying, “(I’m) one of very few people still willing to challenge (him.)” Perhaps this wasn’t a compliment after all, but I do confess that I love a good debate with Martin. I like it for two reasons: one, it keeps him honest on Passive House-related topics (none of us – even great journalists like Martin – always gets it right); and two, it’s a good exercise in sharpening my own critical thinking and debating skills. We all know that Martin is no slouch when it comes to buildings. Exchanging ideas with him is highly engaging, with the added bonus that I typically learn something along the way.

The topic of our most recent joust is one of Martin’s favorite Passive House ‘bones.’ It has seen much heavy chewing since it first surfaced in 2011, when it was tossed up as part of a provocative keynote presentation at the Passive House Northwest Conference in Olympia, Washington. I promised him a longer explanation of my thinking than what I could squeeze into the 140-character Twitter limit. Here it is:

Image 1

Image 1. Source:

To preface this discussion, I include Martin’s now ‘famous’ illustration, used to support his premise (Image 1.) With it, he asks if two inches of insulation, distributed under the foundation slabs of a group of houses, is more effective than only one house with fourteen inches of insulation under it and the rest with none? Martin makes the case that the Passive House Standard – more specifically its energy modeling tool, the PHPP – drives designers to use more insulation than is necessary, and spend more money on this one item, than it currently costs to install a small amount of solar PV to offset the energy saved by the additional inches of insulation needed to meet the Passive House Standard. At the heart of this debate is the hotly contested question and apparent dilemma ‘du jour’: When is it cheaper to add solar PV rather than to install more insulation?

Firstly, let me agree with Martin, to a very limited extent. It’s not worth crunching the numbers, but I’m pretty sure that the distributed insulation shown in his illustration would likely result in more overall energy savings for each total grouping of houses. Duh. (Martin, but this not worthy of you and is a cheap setup.) Neither option is a direct result or outcome of the other.  These scenarios are not mutually exclusive and implementing the Passive House Standard on one house has absolutely no connection to the rest of the houses in your illustration. Adding more insulation to one house DOES NOT PREVENT ANYONE from adding insulation under the slab of another house. There is no shortage of insulation. The argument is a ‘straw man’ and needs to be composted. Here’s a much more realistic scenario:

Image 2

Image 2. Source: Martin’s original sketch with modifications by author.

Let’s not dismiss Martin’s sketch entirely though. It has been very useful, more for the additional questions it has raised and as a good starting point for the very serious problems we all need to solve – and rather quickly. The graphic below (Image 3.) gives an alarming account of how little time we have left to take ‘heroic steps’ in the right direction, issued as part of a recent report by legendary number crunchers, PricewaterhouseCoopers.

Image 3

Image 3. Source:

It’s a great segue into my argument on why I believe Martin is chewing on the wrong two inches of bone in this debate.

You might have heard that earlier this year, California, along with a number of other regions and countries, implemented a carbon tax on gasoline as part of a broader carbon ‘cap and trade’ scheme. Without delving into the finer details, this policy is a game-changer. It commoditized an item that previously had no value, but has repeatedly been proven to have a limit on how much can be produced within the next few decades. (See Image 3.) You don’t need to be a genius, futurist, or even an economist, to recognize that as we move closer to the cap, the value of the allowed carbon approved for release will increase tremendously. Likely exponentially. This leads me to conclude that the real ‘economic comparison’ metric we all should all be using here is not the price of solar PV, but the price of carbon.

Optimizing a building design using the price of solar PV is equivalent to optimizing the design of a communication network using the price of cell phones. (A network has a durable, long-term, reasonably fixed infrastructure value. A cell phone does not.) While very few of us are currently receiving credit for more insulation than what is required by our local codes, it has a durable value. (You cannot take your sub-slab insulation with you when you move, but could theoretically take your solar PV panels.) A small part of my argument hinges on the bet that the size and cost of a solar PV array will be dwarfed by the value of the carbon a building can prove it saves. It’s a calculated bet for sure. I can hear many poo-poohing the idea as too speculative – we’re Americans! We want the cheaper option now!

So here’s the main reason why calculating your insulation investment based on the current price of solar PV is highly problematic: it doesn’t scale and does not apply universally to all projects. The solar PV cost comparison assumes that solar panels can be added to all projects. Not true. On a recent retrofit project in Sunnyvale, California, we optimized the building using the PHPP and found the sweet spot for almost every system and material, but could not ‘zero’ it out because the roof had very little solar access. Large, established redwood trees were planted directly to the south and blocked most of the sun on the roof. It was not sustainable to cut them down. Insulation was the best investment for this property and the owners are now enjoying the side benefit of an incredibly comfortable home in which to live.

The same argument applies to any larger scale building, which we MUST consider if we are going to honestly discuss ‘sustainability.’ The Bullitt Center in Seattle is a perfect example of a building with simply not enough roof space to ‘zero’ out energy use. Its solar array had to extend well beyond its property boundaries to meet its energy needs. A recent study by EcoTrust analyzed the investments made in the building and tracked their annual benefit. It confirms that the efficiency upgrades to the building far exceed those of the solar array (57% vs 18%.) This isn’t me speculating on future carbon value here – the numbers speak for themselves.

Image 4

Image 4. Source:

 Once carbon emissions savings are measured, every little bit of extra insulation will help – whether it’s under the slab or not. Its value will be measured in saved energy, or ‘negawatts’ and will likely not be connected to the cost of energy production (with the exception of how the energy itself is generated and its own carbon saving factor.) I’m betting that our currently mythical ‘Net Zero Energy Homes’ – however one defines that empty integer – will be buried in a marketing graveyard somewhere, right next to Martin’s sub-slab insulation ‘bone.’

However, before we dismiss this idea completely, let’s revisit the small segment of projects that may actually benefit from a cost of solar vs cost of insulation approach. If we study the vast majority of our country’s urban planning design, it reveals that we favor detached homes in remote, idyllic locales. Our sprawling urban planning has created an infrastructure that locks us into a dependence on small vehicle transportation. This means that while many of us are obsessively focused on the house, we’re missing the much bigger picture. If we’re going to attempt to address the possibility of maintaining some form of life here on earth, we have to look at emissions from transportation. (My apologies for the tone here. It’s hard to not sound mildly hysterical when talking about climate change.)

California’s Air Resources Board issued a frightening graphic this year as part of a report on the GHG inventory for 2012 – by Economic Sector. It shows that in California, transportation is responsible for 37% of the total gross emissions from 2012, while residential emissions top out at 7%. Given that most states have a very similar infrastructure to California’s, and given that we are unlikely to rapidly transform our residential infrastructure into one that is car-free, this means even off-grid ‘net zero’ or regular Passive House homes may not be sufficient to reduce our overall carbon emissions to sustainable levels. Whenever possible, we will have to do more, to make up for the many other emissions our chosen lifestyle is responsible for.

Electric vehicles are not a panacea either. While they may serve as a transitional technology, they still require massive infrastructure. Roads, freeways, tunnels, bridges and parking garages all require the use of asphalt and concrete. These materials generate carbon emissions during their manufacturing process – tons of it – and are never included in vehicle Co2 emission calculations. When all these added costs and emissions are finally included in the home energy equation, our current obsessive focus on right-sizing a home’s solar PV to zero out the utility bill will soon look quaintly myopic. Anyone who builds a house now and is debating about adding a few extra inches of insulation under the slab will be wishing they had ditched the granite countertops and spent the extra money on sub-slab insulation. (I’m guessing that retrofitting insulation under a slab won’t become any easier than it is today.) The sketch we should responsibly be looking at and arguing over MUST look more like this:

Image 5

Image 5. Source: Illustration by author.

When the conversation is re-framed and viewed from a perspective that includes all items related to how buildings function, where they are located, and what additional resources and services are needed to make them habitable, we may have a remote chance of fixing our very real climate problems.

This is where the NAPHN14 conference in Maine fits into the story. Given my theory, you can imagine how pleased I was to learn that the Passive House Institute is including this larger perspective in their new direction for the Passive House Standard. In his keynote address at NAPHN14 the founder of the Institute, Dr. Wolfgang Feist, explained the rationale and the calculations behind the two new Standards originally announced at the International Passive House Conference in Aachen earlier this year.

Image 6

Image 6. Source: Prof. Dr. Wolfgang Feist, Passive House Institute.

‘Passive House Plus’ and ‘Passive House Premium,’ consider carbon emissions savings with a multiplier that favors renewable generation and accounts for future developments in seasonal storage capacity for renewable energy supply. The calculation considers the time of the energy generation and use and whether it is stored, or used immediately (See Image 7.) In developing these additions to the ‘Classic’ Passive House Standard, the Passive House Institute has taken a huge leap forward to anticipate, encourage and develop buildings that make a future possible in the age of climate change.

Image 7

Image 7. Source: Prof. Dr. Wolfgang Feist, Passive House Institute.

Image 7

Image 8. Source: Prof. Dr. Wolfgang Feist, Passive House Institute.

Now, when we look back at our starting point, and then look at one last graphic generated by the Global Carbon Project (Image 9) indicating exactly who is responsible for the most carbon emissions across the globe, I’m hoping that the few hundred extra dollars you’ll pay for a couple more inches of sub-slab insulation will start to look like a bargain.

Image 9

Image 9. Source:

Bronwyn Barry, CPHD 
October 3, 2014

NYPH Press release: Passive House standard central to New York City Mayor’s plan




Passive House standard central to New York City Mayor’s plan to reduce carbon emissions 80 percent by 2050.

New York Passive House endorses Mayor’s initiative to scale-up low-energy construction.


New York City October 01, 2014

slide_coverMayor Bill de Blasio’s new plan to dramatically reduce greenhouse gas emissions from city buildings by 2050 relies on Passive House as a guiding standard for new construction and existing building renovation.

The Mayor’s plan, One City: Built to Last, released September 20, states that energy used in New York City’s buildings “…accounts for nearly three-quarters of our contribution to climate change.”  The solution: nearly two-thirds of greenhouse gas reductions must come from more efficient buildings. The plan’s immediate goal is to achieve 35 percent carbon emissions reductions citywide by 2025, establishing a pathway for New York City to reach 80 percent reductions by 2050.

Describing the sweeping transformation required to meet its aggressive targets, the plan notes,  “Overall, the City must cut energy use across all building sectors on average by at least 60 percent from 2005 levels and switch to renewable fuel sources…”. To do this, the report states that New York City will look to “Passive House, carbon neutral, or `zero net energy’ strategies to inform the standards.”  The benefits of the plan will extend far beyond carbon reduction. This is “…an affordability plan, an economic development plan, and a public health plan,” the Mayor argues will make for a healthier, more economically vibrant, sustainable and resilient city for all residents.

Designing to the Passive House standard reduces a building’s energy demand for heating and cooling by 90 percent. Reductions are obtained through high levels of insulation, airtightness, and heat recovery, while designing for proper solar shading, solar heat gain, and internal heat gains. Developed in the 1990s by the Passive House Institute (PHI), located in Darmstadt, Germany, a Passive House may be any building type such as home, school, office, store, or factory.

“The Mayor’s plan is a watershed moment,” says Ken Levenson, President of New York Passive House, a local nonprofit organization affiliated with the Passive House Institute. “Not only does it solidify New York City’s leadership in sustainability, but it makes clear that we can successfully address the climate crisis with advanced standards, like Passive House, which are achievable today.”

Because existing buildings are expected to last well beyond 2050, the plan states that “…increasing the energy efficiency of our existing buildings, in addition to new construction, is the most important step we can take to make deep reductions in our carbon emissions.”

Under the One City: Built to Last plan, the Mayor proposes to invest in high-value projects in 150 to 200 city-owned buildings per year for the next ten years. The City anticipates this investment will prompt the private sector to follow with major low-energy construction activity of its own.

Tens of thousands of Passive Houses have been successfully completed around the world, from a glass office tower in Vienna, Austria, to a hotel near Shanghai, China.  European cities such as Frankfurt, Aachen, and Brussels have led in the regional implementation of Passive House. New York City will be the first North American city, to incorporate Passive House guidelines into its sustainability goals.

The plan estimates this initiative will create 3,500 construction jobs and hundreds of other related industry jobs.  Over ten years, the plan is expected to provide New Yorkers $8.5 billion in cumulative utility cost savings – funds that can be reinvested in the New York economy.





Historical flair meets future-oriented energy concept.

Historical flair meets future-oriented energy concept

Inauguration of new Wilhelminian style Passive House building in Hamburg

(Press Release, Passive House Institute, 25 August 2014)


Hamburg/Darmstadt, Germany. Traditional architectural style and the Passive House Standard work together beautifully – this is demonstrated by a fascinating new build project in Hamburg. The “Haus Winter”, designed in the traditional Wilhelminian style, blends seamlessly into the historical character of the district in which it is located. At the same time, this four-storey apartment block is future-oriented with regard to energy efficiency – made possible with the planning expertise of ZEBAU, a building certifier accredited by the international Passive House Institute. The building was inaugurated on Friday, 22 August with all project participants in attendance.

14997643415_2a793fdce3_zThe new Passive House stands in a residential street next to buildings dating back to the second half of the 19th century. The energy concept lends maximum efficiency through superior insulation and building technology. The structure employs renewable energy sources and regionally supplied, environmentally-friendly materials were used wherever feasible. The building’s underground garage has also been designed with electric-powered vehicles in mind. For increased comfort, building owner Dr. Georg Winter put great emphasis on barrier-free access and a good level of sound-proofing. Additionally, all apartments are fitted with balconies or terraces.

Aspiring to construct a new building combining the Passive House Standard and the Wilhelminian style, typical of many German cities, required close cooperation between all involved. Not only is the facade decorative, it is also exemplary in terms of energy efficiency. In order to avoid thermal bridges, the ornamental balconies were attached to the building using steel anchors. The historical-looking double-casement windows are triple-glazed and large south-facing windows provide the compact structure with high solar gains. Mineral and EPS insulation with an average thickness of 28 mm was covered with mineral plaster and an additional mineral top layer.

Achievement of the Passive House Standard means the “Haus Winter” is extremely comfortable while boasting extremely low energy costs. A balanced indoor climate with a high degree of comfort is provided by the thermally optimised building envelope and the ventilation system. An important aspect here is the permanent supply of pre-heated fresh air, which guarantees the absence of mould and odours while ensuring pleasant air temperatures year-round.

14974663596_c44e3d5944_zOver a third of the total energy consumed in industrialised countries results from the operation of buildings, and most of this goes towards heating. This consumption can be reduced by up to 90 percent using Passive House technology. The remaining demand can be easily met with renewable energies. The certification of a Passive House offers a high degree of planning reliability. The longstanding experience of certifying bodies that have been accredited by the Passive House Institute proves advantageous for the success of the entire project. The certificate itself is proof of the particularly efficient standard of the building.

Press Release as pdf:

14811039198_113d6f036c_z 14811044688_aac8bcd563_z





Passive House technology and Net Zero strategies

Green ‘Net Zero’ Buildings Sound Great. What’s The Catch? segment by Chris Mossa, ran on WNYC Radio August, 13th.  In it Passive House technology was compared favorably to a mild critique of Net Zero strategies and featuring architect Paul Castrucci, a NYPH member.

Listen to the radio segment here:


“When P.S. 62 opens in Staten Island a year from now, it may be the city’s largest science experiment. It will be the first school in the five boroughs, and maybe even the first building of any kind, that can claim to be “net zero” — meaning it produces as much energy as it consumes

“Net zero is an interesting concept when you’re dealing with low buildings— any building that’s three or four stories — you can put solar on the roof,” said Russell Unger, executive director of the Urban Green Council. “It gets a little strange when you have a conversation in a city so known for its high rises.”

A handful of architects and developers in the city share Unger’s perspective. They are focusing more on reducing the energy consumption of their buildings and less on producing energy on site. Some have become adherents of a movement called Passive House — a German design concept that maximizes energy savings, largely through intense insulation. A number of buildings constructed according to these standards have gone up or are underway, including 951 Pacific Street in Brooklyn, a row house that’s expected to come on the market this fall. “

Listen to the broadcast and read the full article here



Parsons graduate architecture students performing case studies of NYC buildings looking for partners

David White of Right Environments, a NYPH member and Parsons faculty, is looking for architects, developers, or building owners to partner with Parsons graduate architecture students performing case studies of NYC buildings.  They will be studying energy use, thermal comfort, air quality, and related building science subjects.

The partner will meet with students to discuss the design approach and potential areas of study; provide drawings; and help coordinate permission for access to the case study building.  The students will execute the study and present it in class, with the partner invited to attend, and deliver a copy of the final report to the partner.

This is a great opportunity for students and practitioners to learn together about the real performance of buildings. If you are interested, please email white [at] newschool [dot] edu.



19th International Passive House Conference 2015 Leipzig

Call for Papers: The International Passive House Conference 2015

Forum for future-proof construction solutions on 17 and 18 April 2015 in Leipzig

(Press Release, Passive House Institute, 1 August 2014)


Experts on energy efficient building and retrofitting can now submit their abstracts for the 19th International Passive House Conference. The deadline runs until 1 October, after which the best projects and solutions will be chosen for presentation on 17 and 18 April 2015 in Leipzig, Germany. The conference will place a special focus on cost-effectiveness and developments in high performance Passive House building components. Detailed information and all necessary submission documents can be found here.

“Every improvement in energy efficient building products makes it that much easier to achieve an energy revolution,” comments Dr. Wolfgang Feist, Director of the Passive House Institute. Triple-paned windows have become standard and in most cases, already present the most economical option. Heat recovery ventilation can also considerably lower energy consumption. According to Feist, it is especially for such systems that more cost-effective solutions are needed.

In addition to high performance components, the conference in Leipzig will also focus on buildings themselves. Innovative construction projects that, for example, stand out due to special use profiles with specific energy requirements or due to challenging climatic conditions will be highlighted. The call for papers is addressed to all those involved with Passive House wishing to present their experiences to an international audience of professionals. A scientific committee will decide which submissions will be accepted by the beginning of November 2014.

Since over 20 years, Passive House stands for quality, comfort and sustainability. As the worldwide platform for energy efficient construction, the Passive House Conference offers high level plenary sessions, workshops for manufacturers and architects, a forum for tradespeople, an exhibition full of highly efficient products, and excursions to built Passive House projects. The conference and accompanying exhibition address architects and builders, product manufacturers, researchers, and other interested stakeholders.

The 19th International Passive House Conference is organised by the Passive House Institute and the University of Innsbruck, Department of Energy Efficient Buildings, in cooperation with the City of Leipzig and the Architectural Chamber of the German State of Saxony. The conference is embedded in the work programmes of two EU-funded projects, PassREg (Passive House regions with renewable energies) and EuroPHit (Step-by-step refurbishment with Passive House components).


Press Release as pdf:

A selection of photos can be found on:


19th International Passive House Conference and Expo:

Conference: Friday and Saturday, 17 and 18 April 2015

Excursions: Sunday, 19 April 2015

Framework programme: beginning Wednesday 15 April 2015

Venue: Congress Center Leipzig CCL

Information on main themes, submissions and registration available at



Passive House and the Public Domain

If there is a question as to what it means to be a Passive House, please see the blog post “What is Passive House?”  But if there is a question as to the history of Passive House, the public domain and trademarks in the US, let’s review:

The Passive House Institute (PHI), founded in the early 1990s, filed for the trademark “Passive House Institute” and its mark in 2007, and both were approved in 2009, see here and here.  PHI also filed for “PHPP”, the cornerstone instrument of Passive House, and it was approved in 2010, see here.

Curiously, in 2009 and early 2010, the Passive House Institute US (PHIUS), who was operating as a contracted service provider to PHI via its EcoLab entity, filed, without the knowledge of PHI, for seven Passive House related trademarks:

    • “Certified Passive House”, which was abandoned later in 2009, see here.
    • “Passive House Institute US”, which was abandoned in 2010, see here.
    • “PHIUS” mark, which was approved in 2010, see here.
    • “PH” mark, which was approved in 2011, see here.
    • “NACPHC”, which was approved in 2012, see here.
    • “PassivHaus Bau”, which was approved in 2011, see here.
    • “CPHC”, which was abandoned later in 2010, see here.


In 2011, for reasons unrelated to trademarks, PHI canceled its contracts with EcoLab/PHIUS. See here.

Then in January 2012 PHIUS again filed to trademark “CPHC” (see here, approved in August) and then six days later in January threatened to sue NY Passive House in regards to the use of the terms “Certified Passive House Consultant” and “CPHC”, see here.   NY Passive House responded that there were no grounds for PHIUS’ claims and that such a suit would be frivolous, see here.

In February 2012 PHIUS filed a lawsuit against ECO Smart Building, P.C., ECO Smart Building LLC. and George D Sullivan, a former board member of PHAUS.  (PHAUS is the association controlled by PHIUS.)  See here.

Then in March of 2012, PHI filed to trademark “Certified Passive House”.   It was published for opposition in Sept 2013 and PHIUS opposed it.  PHI decided to stop paying lawyers, and declined to respond to PHIUS’s opposition and abandoned pursuit of the trademark through a default judgment.  See here.

The End?  Or to be continued?  Only time will tell.



“High cholesterol building”, Urban Green Council July Report

At NYPH we like this July report from Urban Green Council, named “High cholesterol building”. A really great study that outline the current problems with today’s building envelopes, issues with how they are regulated, and the solutions we can pursue now.


“What’s a high cholesterol building? One that’s on a fad diet today but will have severe environmental problems in the future.

It turns out there’s a loophole in our energy code that allows designers to trade off energy-draining envelopes for better mechanical equipment. Decades from now, that equipment will be replaced several times over, while the envelope remains, inefficient as ever.

In fact, our report shows that you would have to go back over 1,000 years to find buildings that used as little insulation as today’s all-glass structures.

But with better glass, designed views, improved construction training, and greener codes, we can have buildings that are as healthy as they are beautiful.”


Read this passionate report here to find out more.




Leading Beyond LEED: NYC Buildings and the Evolving Fight to Consume Less Energy

Here is an article written by Tobias Salinger from the Commercial Observer on the Passive House Revolution in New York City:



“One of the country’s first hyper-efficient affordable multifamily passive houses was failing a basic evaluation early this month and nobody on architect Chris Benedict’s Architecture and Energy Limited team could figure out why. When the innovative foam-and-stucco structure at 803 Knickerbocker Avenue in Bushwick couldn’t hold up to the blower door test that’s a standard trial of airtightness, the architect sent her staff scrambling throughout the six-story, 24-unit building. She and the Ridgewood Bushwick Senior Citizens Council, the project’s developer, anticipate that the building will consume 90 percent less energy than conventional structures, save $23,000 per year in energy bills and beat air pressure assessments. As for the present day, the crew had found the problem: there was a window open on the sixth floor.”

Read the full article here.




Architects and Advocates Predict Passive Revolution

Hundreds of architects, builders and advocates called for residential and commercial buildings of all sizes to consume 75 percent less energy in order to live up to so-called “passive house” standards at a convention yesterday.

The New York Passive House conference and expo at in the Flatiron district attracted both a local and international crowd of those interested in perfecting and popularizing the strict German specifications that make use of controlled ventilation, air-tight installation and innovative façade design to reduce energy costs and usage by massive amounts.

“If architecture is about generosity, then we are probably just doing our job,” said Sabrine Leribaux, an architect with a Brussels-based company called Architectes Associes that operates in a city where all new and significant renovations must adhere to passive standards starting in 2015, in a speech during the daylong event. She added afterwards, “You just have to lift that security lock. Passive house is not European. I grew up in Texas.”

Leribaux and Günter Lang, of the Vienna-based Lang Consulting, presented stunning pictures of completed passive house projects ranging from private homes to large-scale multifamily and commercial developments and passive office skyscrapers to show the prevalence of an architectural movement which they say is becoming the norm in Europe and ought to become the norm here in the city.


Read more here.





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